In this article we will discuss about:- 1. Introduction to Paramoecium 2. Feeding in Paramoecium 3. Digestion.
Introduction to Paramoecium:
Paramoecium is commonly known as slipper animalcule and belongs to sub-kingdom Protozoa and phylum-Ciliophora. The slipper shaped body is covered with cilia. They are found in abundance in stagnant ponds and organic infusions. With the help of cilia, Paramoecium can move very rapidly.
The body of Paramoecium is somewhat cylindrical but flattened. The anterior end is slender and blunt, while the posterior end is thick and pointed. One surface of the body is provided with a groove called oral groove. The oral groove funs obliquely backward and opens into a funnel shaped depression called gullet or cytopharynx through an aperture called cytostome.
Feeding in Paramoecium:
It is a holozoic animal. It feeds on other protozoa, bacteria, minute particles of vegetable and animal matters suspended in the medium. The cilia, covering the body, not only helps in locomotion but also act as receptors for food.
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For working in a synchronous manner, the bases of each cilium are interconnected with others through fibres called neuroneme. Recently, presence of acetyl-cholinesterase is reported from the bases of each cilium, which confirms their activity as sensory receptors. After detecting the presence of food particles, Paramoecium moves over the food.
The cilia, lining the oral groove, perform a great role in capturing food particles. They make a co-ordinated beating, as a result of which a continuous current of water passes down the gullet. The food particles paralyzed by the toxic product of the triculocysts, get collected at the bottom of the gullet. They acquire the shape of a ball by the beating of cilia.
These food-balls or bolus, along with some water, pass through the cytostome to form food vacuoles in the endoplasm. The formation of the food vacuole is a continuous process and as soon as one food vacuole detaches from the gullet, another starts forming.
Digestion in Paramoecium:
The food vacuoles move in a definite course of circulation or cyclosis inside the cytoplasm by its streaming movement. The food vacuoles first travel to the posterior end, then takes a turn and travels anteriorly. After reaching the anterior border of endoplasm they travel back and come to the middle of the body to complete their journey.
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The colour of the contents of food vacuole gradually changes from green to yellow. During their journey within the cytoplasm the food is digested by the lysosomal enzymes in a manner similar to that in Amoeba. Undigested residue of food is thrown out through the cytopyge or cell anus situated on the ventro-posterior surface. The cell anus is only visible during the act of excrement.